September cattle deaths can be a mystery

Wednesday, October 5, 2011

During September there have been a number of cattle deaths around southwest Missouri. The puzzling question has been: what caused the deaths?

At the same time, dry and hot weather depleted much of the forage the cattle would normally have been grazing. About the only green material left was Johnsongrass, according to Eldon Cole, a livestock specialist with University of Missouri Extension.

"Since Johnsongrass was about the only green in fields this summer, it has received much of the blame for the cattle deaths, whether it was the actual cause or not," said Cole.

Johnsongrass is considered a weed by most and is on the Missouri noxious weed list. It is despised by row crop farmers. However, cattle producers respect it and some feel it is an asset to their summer grazing program according to Cole.

Unfortunately, the controversial grass does have the ability to produce cyanogenic glucosides -- most often called prussic acid.

"There are a number of plants capable of accumulating prussic acid, which can kill livestock. Many of those plants are in the sorghum category," said Cole.

Under normal conditions, these prussic acid producers contain low levels of the toxin.

"The dry, hot summer was not normal and could have resulted in an above average production of prussic acid which may have contributed to the cattle deaths, although it's difficult to prove," said Cole.

"The greatest risk, and what may have been a factor in some deaths this year, is when lush Johnsongrass standing less than 20 to 24 inches tall is grazed by cattle that are naive to it," said Cole.

Cole also notes that is important to remember that there are other factors that could be causing the high number of deaths this year such as nitrates, hot weather and anaplasmosis.